Telephone calling dial



March 19, 1940. 5, AM 2,194,306

TELEPHONE CALLING DIAL I Filed May 20, 1958 3/ FIG.

INVENTOR 7. s. HUXHAM A T TORNE Y Patented Mar. 19, 1940 UNITED STATES PATENT oF TcE TELEPHONE CALLING DIAL Trevor S. Huxham, Chatham, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N.. Y., a corporation of New York Application May 20, 1938, Serial No. 209,023

6 Claims. (01. 179-90) ward through the casing l and may bemanually This invention relates to telephone calling dials and more particularly to finger wheels for telephone calling dials. I The object of the invention is to prevent fracturing of a frangible finger wheel.

, A feature of the invention resides in a flexible support for the finger wheel.

In the drawing:

Fig. l is a side elevational view partly in section of a telephone calling dial embodying the invention; Y i

I Fig. 2 is an exploded view in perspective of the finger wheel and certain other parts directly associated with the finger wheel; l l Fig. 3 is a top plan view of the calling dial shown in Fig. 1 and drawn to a reduced scale relative to Fig. 1; and

Fig. 4 is a side elevational view partly in section of a portion of the finger wheel taken on the line 4-4 in Fig. 3. Fig. 4 is drawn to the same scale as Figs.,1 and 2. In a common and well-known type of tele phone calling dial a manually rotatable finger wheel is provided to control the sending of signals to a central station to set up adesired call connection. The finger wheel is a disc having therein a plurality of finger holes and is supported on an operating shaft of the telephone calling dial. The finger wheel is usually made of metal and is relatively strong and durable. It is rather expensive to manufacture however, due to the finishing operations required in its production.

Eiforts have been made to reduce the cost of the finger wheel by making the finger wheelof molded insulation material since such material is relatively inexpensive and requires very little, if any, finishing operation beyond the molding operation. Synthetic resins and other easily molded substances and even glass have been tried for the finger wheel material. Such materials, however, have been found to be too frangible for the conditions met in service when the finger wheel is directly connected to the operating shaft of the calling dial.

In this invention a flexible support is provided between the finger wheel and the operating shaft or the calling dial. I

The telephone calling dial as shown in Fig. 1

comprises a casing I and a finger wheel 2, the

finger wheel 2 being supported above the casing 'l. The finger wheel 2 is mounted. on an operating shaft 3 by means of a flexible mounting 4, the structure of which will be subsequently de- 5 scribed, The operating shafts extends downoperated by means of the finger wheel 2 to wind up a spring 5. l The spring 5 serves as a motor to return the finger wheel to normal position and 1 as a driving means foracontact controlling de- I vice 6 which operates on spring contacts I to control the sending of impulses over a line system to set up a desired call connection. A sys-\ tem of gears, not shown, but'enclosed within the casing I is provided to" transmit the driving force of the spring 5 to the contact controlling device 6. A centrifugal governor 8 is included in the device to slow down the unwinding movement of the spring 5 and the return of the finger wheel 2 to required normal position; A ring shaped dial 9 bearing groups of letters and numerals on its upper face is supported in the top portion of the casing l, the groups being arranged in positions to be observed through finger holes in-the finger wheel 2, all of which is well known and understood in the art.

The finger wheel 2 is made of material which may be readily molded. to required form in suit' able molds. some of the synthetic resin compositions and phenol condensation materials have been found suitable for finger wheel construction. The particular material employed in the finger wheel construction is a matter of choice. For the purpose of illustration of the invention, however, and not limiting the invention to any particular material, it will be assumed that the finger wheel 2 is made of synthetic resin since such material may be readily molded to required form and material of thistype is rather frangible. The finger wheel 2 comprises'a disc portion l0 and a hub portion H, the hub portion ll exdisc portion Ill. The disc portion l 0 is apertured tending upward from the upper surface of the to provide a series of finger holes l2 'to facilitate manual rotation of the finger wheel 2. The internal diameter of the hub portion l l of the fine ger wheel 2 is much larger than the diameter of the operating shaft 3. Projecting inwardly from the inner wall surface of the hub portion l i are four spaced shoulders E3 the upper surfaces of as shown at Hi, the curvature being in a direction transverse to that of the curved inner ends l5 of the lugs M. The shoulders 3 and the lugs N form, in a sense, an irregular ring of projections extending inwardly from the inner surface of the hub portion H. As clearly shown in Fig. 2 it will be seen that the shoulders 53 extend a greater distance inwardly from the hub portion ll than the lugs i and that the upper surfaces of the shoulders. E3 are above the upper surfaces of the lugs i i. A raised ledge ii is provided on the top of one of the shoulders 53, the ledge ll extending over a portion of the in clined upper surface of the shoulder i3. An annular groove ill is formed in the inner wall surface of the upper portion of the hub portion i i of the finger wheel 2, the groove i8 extend rectly above the upper surface of the ledge H. The outer edge of the fineer wheel 2 is extended downward to provide a slnrt portion l5.

The finger wheel 2 is not directly attached to the operating shaft 3 of the calling dial but is mounted thereon by means of the flexible mounting 4. The flexible mounting 1 comprises crossshaped members 29 and 5?? of iiezdble material having sufiicient stiifness to support the finger wheel 2. The members 2! and 26 are made in the form of a Greek cross and are laid together in laminated form with the portions of one extending over corresponding fu "er portions of the other. The member F1- is e fiat so that the finger portions 22 and the central portion 23 all lie in the same plane. The member 2| has finger portions 24 slanting upward from the central portion 25 and 'te rnin rug at the free ends in bat portions 25 s'hich in spaced parallel relation with the associated finger portions 22 of the member 28. The central p .rtions 23 and 25 of the respective members and El 4 are fastened together and are apertures. to accommodate the upper end portion of the operating shaft 3. The central portio.-s of the memhere 2! and 2! rest on a flange Z? on the shaft 3 and are held against removai efron by a nut 28 screwed to the upper end of the shaft A washer 29 is interposed between the nut 28 and the central portion of member to insure against separation of the cer ral no of the members 29 and 2 i. The aperture in washer is formed to accommodate flat side portions on the upper portion of the shaft and the apertures in the central portions oi the members it! and 2| are likewise formed to prevent relative rotation of the parts. The finger portions of the members 2? and 2E frictionally one? e the lugs H1 in the hub portion of the finger Wheel ,2 and extend across the space between the lugs M and the flange 2'! of the shaft 3 and serve as flexible The finger porsupports between these parts. tions 22 of the member 2i; bear surfaces of the lugs i l. The flat portioi the fingers 24 of the member 26 ders iii. The width of the finger portions of the members .26 and ii is made substantially the same as the Width of the lug and the shoulders l3 are made higher than the lug M to prevent lost motion between the finger heel 2 and the flexible support a in a rotational direction.

When the flexible support 2- is being assemoled with the finger wheel 2, the member it? is placed with its finger portions bearing against under surfaces of the lugs M. The member 23 is then placed within the hub portion H with the flat portions 26 of the fingers Gi l resting on the upper surfaces of the lugs i Pressure is then applied to the central portions of the members 20 and 2 l until the central portions come together. The central portions are then fastened together by any suitable means. For instance, if the members 2C and 2% are made of sheet metal, the central portions be welded together. In the assembling operation of these parts, spring pressure is developed the ringer portions of the members 20 and 2! so that there is a clamping action of the o gainst the lugs M. The washer ma; or otherwise fastened to the upper Sui'ic: i th'v central portion of the member it at the tune time as the members and 25 a; together.

A station identif' atica card 3! comprising a fiat disc rests on e top of the shaft 3 and on the inclined upper surfaces of the shoulders l3. The card 3% is covered by a transparent disc 32. A split ring having an outside diameter only slightly less the diameter of the groove l8 and adapted to be sprung into the groove it bears P "net the upper port on of the transparent disc 32 and holds the c d 7'?! and the disc 32 in place. e station i .=cation card 3! and the tra cut away at one point as i to accommodate the ledge which "he cut-away porti r parts 3! and 32 relative The upper surfaces oi aclined and the operating e the plane of the ii! to give the -d the disc 32 an he). the card 25 and on the ring 33. 5- fleidbly supports the ting ait 3 of the on stress 5 are ap- The linger wheel 2 al plane as shown without danger of nee movement to by the flexible mountin 5-. e a telephone instrument bear the calling dial described is dropped to a floor 51 the frangible finger wheel is protected f: effects of the resulting ar by the mounting i. The flexible mountire 1 y frictional engagement with the fli I? and may be made of material havin .ent temperature coefficient of exp n that of the finger Wheel. wt'zel I! may be made of synthet c i e. ible mounting 1 may be m of the frictional conne als of the l identifi dly bo-..

finger t1. nee]. E2 on calling dial and will hen plied to may tilted in the dotted li' fracturing the such a positi degrees "bout causing .ressures or stresses .,r-o.ble downward '1 to a finger wheel rot; ,ing th fin- In 35. In this event the the h or the presslirt portion under the u"; oer portion r instance, dotted line of he downward movement. As shown in the dotted line position the finger wheel 2 is raised on one side and on the opposite side is in engagement with the upper portion of the casing I. No fracturing strain, however, has been applied to the finger wheel 2 during I its movement to the position shown since most of the pressure applied is taken up by the finger portions of the flexible mounting 4.

The finger wheel 2 may, therefore, be made of synthetic resin or other frangible molding material and still stand the conditions met in service by instruments of this kind.

It is obvious that the washer 29 may be dis pensed with and the members 20 and ill, need not be attached to each other, but that the members 20 and El may be simply clamped between the nut 28 and the flange 21 and that other changes may be made in the structure without departing from the spirit of the invention.

What is claimed is: I

1. In a telephone calling dial, in combination, a rotatable shaft, a finger wheel and a flexible support in frictional engagement with said finger wheel and mounted on said shaft.

2. In a telephone calling dial, in combination, a rotatable shaft, a finger wheel, a central hub portion on said finger wheel, and a fingered support of flexible material frictionally engaging said hub portion and mounted on said shaft.

3. In a telephone calling dial, in combination, a rotatable shaft, a finger wheel, a hub portion on said finger wheel, spaced lugs extending inwardly from said hub portion, and a fingered support of flexible material in frictional engagement with said lugs and mounted on said shaft.

4. In a telphone calling dial, in combination, a rotatable shaft, a finger wheel, a hub portion on said finger wheel, spaced projections extending inwardly from said hub portion, a laminated support of flexible material mounted on said shaft, and spaced fingers arranged in pairs on said support and in frictional engagement with said projections.

5. In a telephone calling dial, in combination, a rotatable shaft, a finger wheel of frangible material, a hub portion on said finger wheel, a series of spaced shoulders extending inwardly from said hub portion, a series of spaced lugs alternated with said shoulders and projecting inwardly from said hub portion, a support of flexible material'mounted on said shaft and divided finger portions on said support in frictional engagement with said lugs and extending between said shoulders.

6. In a telephone calling dial, in combination, a rotatable shaft, a finger wheel of frangible material, a hub portion on said finger wheel, a series of spaced shoulders projecting inwardly from said hub portion, a series ofspaced lugs alternated with said shoulders and projecting inwardly from said hub portion, a laminated support of flexible material mounted on said shaft, and pairs of upper and lower finger portions on said support passing between said shoulders and in frictional engagement with said lugs.

TREVOR S. HUXHAM. 

